Inductors are passive electrical components that are configured to generate a magnetic field that stores energy. Inductors are used in a wide variety of integrated circuit (IC) applications, such as, for example, voltage regulators and many radio frequency (RF) circuits. At least some known inductors can be built directly on integrated circuits using existing integrated chip fabrication processes.
When designing the inductor, it is important to consider the inductance as well as the quality value or factor (Q factor) of the inductor. The inductance of an integrated inductor is a measure of the amount of energy stored in an inductor. The Q factor is a ratio of the amount of energy stored in an inductor to the amount of energy dissipated in the inductor. An ideal inductor has a relatively high Q factor.
In at least some known inductors, the metal layers are stacked and the distance between the layers can be approximately 0.2 to 1 microns. In order to save, for example, chip area, the metal layers should be relatively close to one another. However, as the distance between the metal layers decreases, the capacitance and resistance substantially increase. Such an increase results in a low resonance frequency which can cause a low Q factor.